Small rodents such as mice, rats, guinea pigs, and hamsters are used in scientific research and they are sometimes kept as pets by children. Typically, such animals are held in small cages where they are provided with nesting material along with food and water. Solid food is kept in a feeding device. So that the cage remains dry and relatively orderly, liquids, such as water and medicines, are usually stored in a special bottle with a dispensing device that allows small portions to be released to the animal.
A common type of dispensing device, widely used in the laboratory animal industry, is a sipper tube that is connected to a bottle filled with liquid. The tube points downward and is accessible to the animal. Often the hole in the tube is relatively small and, therefore, surface tension, along with a partial vacuum that is created in the bottle, prevents liquid from flowing freely from the bottle. Other sipper tubes include ball bearings disposed therein to block the hole at the bottom of the tube. The bearing is free to move—and when it does—it allows liquid to exit in a controlled manner.
In the prior art, it is well known that a sipper tube—such as the one just described—can be coupled to a bottle with a stopper made of rubber, neoprene, or another similar material. The stopper is placed in the mouth of the bottle where it is held by friction fit. Similarly, a hole in the stopper is dimensioned to hold the sipper tube by friction fit. With the bottle inverted, the sipper tube is accessible to an animal, and limited amounts of liquid can flow out of the bottle as needed.
The use of a simple friction fit between the stopper and the bottle has at least one major limitation. Because the bottle is inverted, the weight of the liquid tends to loosen the stopper. Furthermore, the stopper is loosened by vibrations and motion caused by an animal using the bottle. These loosening effects may eventually cause the stopper to come apart from the bottle, allowing liquid to escape. In some cases, animals attempt and sometimes succeed in removing stoppers from the bottle. In order to avoid these potentialities, stoppers are usually inserted into the bottle by hand with relatively high force. However, this action may cause health problems, such carpal tunnel syndrome, for a person who must repetitively insert stoppers into bottles. After all, typical laboratories utilize large quantities of these bottles and stoppers.
One example of a removable cap assembly is shown in U.S. Pat. No. 6,042,440 to Murray et al. This invention makes steps to overcome the limitations—discussed above—of standard, friction fit stoppers. The patent teaches an assembly that includes a stopper which has a neck disposed between two lip structures. The neck is dimensioned to receive a flange that is disposed on a cap. Finally, a sipper tube is provided which is positioned within a hole in the stopper, to extend through the opening. The patent also teaches a cap that needs to be turned only 180 degrees in order to seal the bottle.
While the device described in this patent helps to solve some problems inherent in prior art, at least one major limitation is intrinsic in its design. The lip and neck structure, which is held in place by a single circumferential flange, tends to lack rigidity. Thus, the problem remains that the sipper tube can be wriggled, allowing leakage of the bottle contents or the removal of the sipper tube. Moreover, wriggling of the sipper tube can allow air to enter the bottle, eliminating the partial vacuum and causing liquid to flow freely from the sipper tube. An additional concern with this prior art device is that the upper lip is exposed on the outside of the cap. The lip tends to collect dirt and germs which can be harmful to the animals or those handling the bottle assemblies.
Another problem with this prior art device is manner in which the seal is crated after the cap is turned 180 degrees. The 180 degree turn is achieved by having a single continuous thread on both the bottle and cap. The cap bottoms out after the cap has turned 180 degrees. As such, the cap is compressed along only half of the sealing surface.
Thus, what is needed is an improved removable cap assembly that overcomes prior art limitations. Specifically, these limitations include the rigidity and security with which the sipper tube is held by a stopper in the bottle. Additionally, problems with regard to cleanliness stem from design features in the prior art.